A cold sore onyour lips or on your genitals is referred to herpes, Ithink you might've heard that term before, andit's caused by a virus referred to as the herpes simplex virus. The herpes simplex virus orHSV comes in two flavors. There's HSV1, and there's HSV2. It used to be believed thatHSV1 mainly caused oral lesions, so I'll write up here oral,and HSV2 mainly caused
genital sores or genital lesions. But more recently, it's beennoted that HSV2 can cause oral sores, and HSV1 cancause genital sores as well. And in fact, this typeof infection is so common that 90% of Americans areexposed to this by 50 years old. So they're exposed in a variety of ways, which makes herpes simplex virus a sexually transmitteddisease, so if we talk
about the modes oftransmission or how it spreads from one infected personto an uninfected person, that can include sex,which can be oral sex, vaginal sex, or even anal sex. Childbirth is an importantmode of transmission as well. If an infected mother has any active sores while she's giving birth,her baby can get exposed to the herpes virus.
Or even outside of childbirth,any contact with open sores can cause transmission of the virus. Or if you were to come intocontact with the bodily fluid that's infected with HSV in another way, so if you were to share bodily fluids, like a healthcare workerthat gets stabbed by a needle that was used to draw bloodfrom a patient that has HSV, that counts as a modeof transmission as well.
And we'll talk moreabout that in a second. Generally, from the firstpoint of infection right here, so I'll write infection, and we'll make this type of timeline right here. It takes about four to seven days before the first sores appear. And once they're there,it takes about 10 days for them to heal up and go away.
There are six main symptomsthat I'll mention here, and we'll start off here, where you might recognizethis is somebody's lips right here, and they've developeda cold sore right there. The technical term for this,because it's caused by herpes, we call it herpes labialis. So for shorthand, I'lldenote this triangle to represent the HSV virus.
Pathophysiology of herpes
Narrator When we're talking about the pathophysiology of a disease, we're trying to figure out howthat disease causes symptoms. So in the case of herpes,or the herpes simplex virus, we're trying to figure outhow the virus infects cells, and causes symptoms. So let's take a look atthis skin cell over here, this is a cell that may live on your lips,
and here's the nucleus, I'm gonna draw it dotted so we can see what's going on inside. And in there there's going to be some DNA. And I'll draw it like thiseven though DNA is a lot more tightly wound than it is here. Then I'll label these thingsso this dotted line here, I mentioned was the nucleus.
Or we can also refer to itas the nuclear envelope. And then on the inside, this guy is our cell's DNA. It's our own DNA or our nucleicacid that lives in there. Now let's imagine thiscell's going to be infected by the herpes virus soI will use this triangle to symbolize herpes, and so this triangle or thisvirus will come and attach
on to the cell membrane here. And within the cell, theherpes has its own DNA. The viral DNA that existsas well as some proteins that are in here and I'llexplain in a few minutes what these proteins help it do. But just realize firstoff this green border, the triangle on the outside, is a nucleocapsid.
This helps the virus injectthe DNA and the proteins into the cell, like we'll see in a minute. Right here we've got some proteins, as I'll mention in a few minutes. These help incorporate the viral DNA into the human or host DNA. And finally this yellow strand right here is the viral DNA.
So this is the DNA ofthe herpes simplex virus. And so our first step hereis that the nucleocapsid has proteins that helpinject the viral DNA and these proteins into the human cell. Which means that as I'll draw right here, is to inject viral DNA. So once we do that, letme just draw our cell again over here.